基于3D有限元仿真的钻杆接头应力分析与集中系数研究

Stress analysis and concentration coefficient of drill pipe joints based on 3D finite element simulation

摘要:

钻井工程中，钻杆接头螺纹连接处失效占比高达86%，是钻柱失效的主要风险部位。为深入分析接头应力分布及集中特性，本研究基于三维有限元仿真，对API标准单台肩与双台肩钻杆接头在轴向和扭转载荷下的应力进行了对比分析，并针对NC50型接头计算了轴向与扭转应力集中系数。研究发现：单台肩螺纹最大应力集中于螺纹啮合部第一圈齿根处；双台肩螺纹的最大轴向应力和剪切应力显著低于单台肩螺纹（分别约24%和27.3%），尤其在高扭矩下性能优势更明显；NC50接头的轴向应力集中系数为4.21，扭转应力集中系数为3.73。本研究成果为钻杆接头性能优化设计、钻井系统应力精确计算及疲劳寿命预测提供了重要依据。

Abstract:

In drilling engineering， failures at the threaded connections of drill pipe joints account for up to 86%， making them the primary risk area for drill string failure. To conduct an in-depth analysis of joint stress distribution and concentration characteristics， this study， based on 3D finite element simulation， performed a comparative analysis of the stress in API standard single-shoulder and double-shoulder drill string joints under axial and torsional loads. Furthermore， the axial and torsional stress concentration coefficients for the NC50-type joint were calculated. The findings indicate that： the maximum stress in single-shoulder threads is concentrated at the root of the first thread in the thread engagement area； the maximum axial and shear stresses in double-shoulder threads are significantly lower than those in single-shoulder threads， with reductions of approximately 24% and 27.3%， respectively， exhibiting a more pronounced performance advantage， especially under high torque； the axial stress concentration coefficient for the NC50 joint is 4.21， and the torsional stress concentration coefficient is 3.73. The outcomes of this research provide a significant basis for the performance optimization design of drill pipe joints， precise stress calculation of the drilling system， and fatigue life prediction.